Glycosylation of endothelial lipase at asparagine-116 reduces activity and the hydrolysis of native lipoproteins in vitro and in vivo

Robert J. Brown, Gwen C. Miller, Nathalie Griffon, Christopher J. Long, Daniel J. Rader
2007 Journal of Lipid Research  
We previously identified that four of five putative N-linked glycosylation sites of human endothelial lipase (EL) are utilized and suggested that the substitution of asparagine-116 (Asn-116) with alanine (Ala) (N116A) increased the hydrolytic activity of EL. The current study demonstrates that mutagenesis of either Asn-116 to threonine (Thr) or Thr-118 to Ala also disrupted the glycosylation of EL and enhanced catalytic activity toward synthetic substrates by 3-fold versus wild-type EL.
more » ... ld-type EL. Furthermore, we assessed the hydrolysis of native lipoprotein lipids by EL-N116A. EL-N116A exhibited a 5-fold increase in LDL hydrolysis and a 1.8-fold increase in HDL 2 hydrolysis. Consistent with these observations, adenovirus-mediated expression of EL-N116A in mice significantly reduced the levels of both LDL and HDL cholesterol beyond the reductions observed by the expression of wild-type EL alone. Finally, we introduced Asn-116 of EL into the analogous positions within LPL and HL, resulting in N-linked glycosylation at this site. Glycosylation at this site suppressed the LPL hydrolysis of synthetic substrates, LDL, HDL 2 , and HDL 3 but had little effect on HL activity. These data suggest that N-linked glycosylation at Asn-116 reduces the ability of EL to hydrolyze lipids in LDL and HDL 2 .-Brown, R. J., G. C. Miller, N. Griffon, C. J. Long, and D. J. Rader. Glycosylation of endothelial lipase at asparagine-116 reduces activity and the hydrolysis of native lipoproteins in vitro and in vivo. J. Lipid Res.
doi:10.1194/jlr.m600535-jlr200 pmid:17322565 fatcat:nk5ejpzfubc6jpnvolktrw7vju